<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python documentation Index' />
<link rel="first" href="lib.html" title='Python library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="prev" href="node538.html" />
<link rel="parent" href="node533.html" />
<link rel="next" href="module-socket.html" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name='aesop' content='information' />
<title>17.1.3.6 Replacing popen2.*</title>
</head>
<body>
<div class="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="17.1.3.5 replacing os.popen*"
  href="node538.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="17.1.3 replacing Older Functions"
  href="node533.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="17.2 socket  "
  href="module-socket.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="node538.html">17.1.3.5 Replacing os.popen*</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="node533.html">17.1.3 Replacing Older Functions</a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="module-socket.html">17.2 socket  </a>
</div>
<hr /></div>
</div>
<!--End of Navigation Panel-->

<h3><a name="SECTION0019136000000000000000">
17.1.3.6 Replacing popen2.*</a>
</h3>

<p>
<span class="note"><b class="label">Note:</b>
If the cmd argument to popen2 functions is a string, the command
is executed through /bin/sh.  If it is a list, the command is directly
executed.</span>

<p>
<div class="verbatim"><pre>
(child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
==&gt;
p = Popen(["somestring"], shell=True, bufsize=bufsize,
          stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
</pre></div>

<p>
<div class="verbatim"><pre>
(child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
==&gt;
p = Popen(["mycmd", "myarg"], bufsize=bufsize,
          stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
</pre></div>

<p>
The popen2.Popen3 and popen2.Popen4 basically works as subprocess.Popen,
except that:

<p>

<ul>
<li>subprocess.Popen raises an exception if the execution fails

<p>
</li>
<li>the <var>capturestderr</var> argument is replaced with the <var>stderr</var>
      argument.

<p>
</li>
<li>stdin=PIPE and stdout=PIPE must be specified.

<p>
</li>
<li>popen2 closes all file descriptors by default, but you have to
      specify close_fds=True with subprocess.Popen.
</li>
</ul>

<div class="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="17.1.3.5 replacing os.popen*"
  href="node538.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="17.1.3 replacing Older Functions"
  href="node533.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="17.2 socket  "
  href="module-socket.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="node538.html">17.1.3.5 Replacing os.popen*</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="node533.html">17.1.3 Replacing Older Functions</a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="module-socket.html">17.2 socket  </a>
</div>
</div>
<hr />
<span class="release-info">Release 2.5.1, documentation updated on 18th April, 2007.</span>
</div>
<!--End of Navigation Panel-->
<address>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</address>
</body>
</html>
